piece of one's mind
Frank and severe criticism, censure, as in Chuck was furious and gave him a piece of his mind. The word piece here is used in the sense of "portion," but the portion of the mind alluded to always has a negative opinion. [Second half of 1500s]
piece of one's mind, (to give someone) a
To express one’s disapproval quite plainly; to give one’s candid opinion. This term has been around since the sixteenth century. John Dryden used it in his play The Maiden Queen (1667, 2.1): “I have told her a piece of my mind already.”